External speech processor unit for an auditory prosthesis

ABSTRACT

A cochlear implant system comprising an external component having an external speech processor unit, and an internal component. The speech processor unit monitors one or more parameters, and the speech processor unit is configured to reduce the power consumption of the cochlear implant system in the absence of one or more parameters.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is continuation of co-pending and commonly ownedU.S. patent application Ser. No. 10/962,441, filed Oct. 13, 2004, whichclaims priority from AU Provisional Patent Application No. 2003905570,filed Oct. 13, 2003. The contents of these applications are herebyincorporated by reference herein.

BACKGROUND

1. Field of the Invention

This present invention is generally directed to auditory prosthesis, andmore particularly, to an external speech processor unit for an auditoryprosthesis.

2. Related Art

Hearing loss, which may be due to many different causes, is generally oftwo types, conductive and sensorineural. In some cases, a person suffersfrom hearing loss of both types. Conductive hearing loss occurs when thenormal mechanical pathways for sound to reach the cochlea, and thus thesensory hair cells therein, are impeded, for example, by damage to theossicles. Individuals who suffer from conductive hearing loss typicallyhave some form of residual hearing because the hair cells in the cochleaare undamaged. As a result, individuals suffering from conductivehearing loss typically receive an acoustic hearing aid. Acoustic hearingaids stimulate an individual's cochlea by providing an amplified soundto the cochlea that causes mechanical motion of the cochlear fluid.

In many people who are profoundly deaf, however, the reason for theirdeafness is sensorineural hearing loss. Sensorineural hearing lossoccurs when there is damage to the inner ear, or to the nerve pathwaysfrom the inner ear to the brain. As such, those suffering from someforms of sensorineural hearing loss are thus unable to derive suitablebenefit from conventional acoustic hearing aids.

It is for this purpose that cochlear implant systems have beendeveloped. Cochlear implants systems, sometimes referred to as cochlearimplants herein, bypass the hair cells in the cochlea and directlydeliver electrical stimulation signals to the auditory nerve fibres,thereby allowing the brain to perceive a hearing sensation resemblingthe natural hearing sensation normally delivered to the auditory nerve.

Cochlear implant systems generally consist of two components, anexternal component, and an internal or implanted component. The internalcomponent receives signals from the external component that are used toprovide a sound sensation to a user or recipient of the cochlear implantsystem, generally and collectively referred to as a recipient herein.

The external component includes a microphone for detecting sounds, suchas speech and environmental sounds, a speech processor unit thatconverts speech into a coded signal, a power source such as a battery,and an external transmitter antenna coil. The speech processor unitoutputs a coded signal representing a sound received by the microphonewhich is transmitted transcutaneously to a stimulator/receiver withinthe internal component. The stimulator/receiver unit is situated withina recess of the temporal bone of the recipient. This transcutaneoustransmission occurs via the external transmitter antenna coil which ispositioned to communicate with an implanted receiver antenna coil of theinternal component. This transcutaneous transmission link is used totransmit coded signals output by the speech process unit and to providepower to the internal components. The transcutaneous link is, normally,in the form of a radio frequency (RF) link, but other such links havebeen proposed and implemented with varying degrees of success.

The implanted stimulator/receiver unit includes, in addition to thereceiver antenna coil that receives coded signals and power from theexternal processor component, a stimulator that processes the codedsignals. The stimulator outputs electrical stimulation signals to anintracochlea electrode assembly which applies the stimulation signalsdirectly to the auditory nerve, thereby producing a hearing sensationcorresponding to the originally detected sound.

The external component is configured to be worn by the recipient. Forexample, in certain circumstances, the external component may be carriedon the body of the user, such as in a pocket of the user's clothing, abelt pouch or in a harness, while the microphone is mounted on a clipmounted behind the ear or on the lapel of the user. More recently, thephysical dimensions of the speech processor unit have been able to bereduced allowing for the speech processor unit to be housed in arelatively small unit capable of being worn discreetly behind the ear ofthe user, sometimes referred to as a Behind-The-Ear (BTE) unit or BTE.In this arrangement, the external transmitter antenna coil is stillpositioned on the side of the user's head to allow for the transmissionof the coded sound signal and power from the sound processor to theimplanted stimulator unit.

BTEs have provided a degree of freedom and subtlety for the recipientwhich has not traditionally been possible with body worn devices. Thereis no longer a need for extensive cables connecting the body wornprocessor to the transmitter antenna coil, nor is there a need for aseparate microphone unit or battery pack, as the BTE unit contains allthe components in one housing. One common feature of all conventionalBTE units is the provision of a dedicated mechanical switch for turningthe unit on or off. Such a switch is typically small in size anddifficult to manipulate, especially in the case of elderly recipients orthose who are not very dexterous. Continuous use of the switch causesmechanical fatigue resulting in the switch failing to operate andrequiring repair or replacement.

SUMMARY

In one aspect of the present invention, a method of reducing the powerconsumption of a cochlear implant comprising an external componentincluding a speech processor unit configured to be worn by a recipient,and an internal component is provided. The method comprises: monitoringby the speech processor unit the proximity of the external componentunit to the internal component; determining by the speech processor unitthat the external component is not in proximity to the internalcomponent; and causing the external component to enter an idle state ofreduced power consumption when the speech processor unit determines thatthe external component is not in proximity to the internal component.

In another aspect of the present invention, a method of reducing thepower consumption of a cochlear implant comprising an external componentincluding a speech processor unit configured to be worn by a recipient,and an internal component is provided. The method comprises: monitoringby the speech processor unit motion of the speech processor unit;determining that the speech processor unit is not motion; and causingthe external component to enter an idle state of reduced powerconsumption when the speech processor unit determines that the speechprocessor unit has ceased movement.

In a still other aspect of the present invention, a cochlear implant isprovided. The cochlear implant comprises: an internal componentconfigured to be implanted in a recipient of the cochlear implant; andan external component including a speech processor unit configured to beworn by the recipient, the speech processor unit comprising: a signalprocessor configured to determine if the external component is inproximity to the internal component, and to place the external componentin an idle state of reduced power consumption when the externalcomponent is not in proximity to the internal component.

In another aspect of the present invention, a cochlear implant isprovided. The cochlear implant comprises: an internal componentconfigured to be implanted in a recipient of the cochlear implant; andan external component including a speech processor unit configured to beworn by the recipient, the speech processor unit comprising: a monitorconfigured to detect motion of the speech processor unit; and a signalprocessor configured to place the external component in an idle state ofreduced power consumption when the monitor determines that the externalcomponent has ceased movement.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present invention are described below with referenceto the attached drawings, in which:

FIG. 1 is a schematic representation of a cochlear implant system, inaccordance with an embodiment of the invention;

FIG. 2 is a block diagram of a cochlear implant system, in accordancewith the invention, for the implant of FIG. 1;

FIG. 3 is a block diagram of a motion detecting switch, in accordancewith embodiments of the present invention;

FIG. 4 is a block diagram of the pause-and-gate circuit of FIG. 2. inaccordance with embodiments of the present invention;

FIG. 5 is a flow chart illustrating the operations performed by thespeech processor unit of FIG. 2, in accordance with embodiments of thepresent invention; and

FIG. 6 is a flow chart illustrating the operations performed by a speechprocessor unit in accordance with embodiments of the present invention.

DETAILED DESCRIPTION

Embodiments of the present invention are generally directed to acochlear implant comprising an external component including a speechprocessor unit configured to be worn by a recipient, and an internalcomponent. The speech processor unit is configured to monitor one ormore parameters and to reduce the power consumption of the externalcomponent when one of the parameters are absent.

More specifically, the speech processor unit monitors one or moreparameters that include, for example, the proximity of the externalcomponent to the internal component and motion of the speech processorunit. The absence of one or more of these parameters provides anindication that the external component is not being used, for example,due to the recipient being asleep, bathing, etc. As described in greaterdetail below, if one or more of the parameters are absent, the speechprocessor unit is configured to reduce the power consumption of theexternal component. In certain embodiments, the speech processor unitcauses the external component to enter an idle state of reduced powerconsumption.

A cochlear implant system 10 in accordance with embodiments of thepresent invention is illustrated in FIG. 1. As shown, cochlear implantsystem 10, sometimes referred to as cochlear implant 10, herein,comprises an external component 14, and an internal component 18implanted in a recipient. External component 14 includes a microphone 36for detecting sounds, such as speech and environmental sounds, and anexternal speech processor unit 12 that converts speech into a codedsignal. External component 14 further includes a transmitting device, inthe form of a transmitter antenna coil 16.

Internal component 18 includes an implanted receiver and stimulator unit20 implanted in a recess in a temporal bone of a recipient, and aimplanted receiver antenna coil 22. Implanted receiver antenna coil 22and stimulator unit 20 are sometimes collectively referred to as astimulator/receiver unit.

Speech processor unit 12 outputs a coded signal representing a soundreceived by microphone 36 which is transmitted transcutaneously toreceiver antenna coil 22 within internal component 18. Thistranscutaneous transmission occurs via external transmitter antenna coil116 which is positioned to communicate with receiver antenna coil 22.This transcutaneous transmission link is used to transmit the codedsignals output by speech process unit 12 and to provide power tointernal component 18. The transcutaneous link is, normally, in the formof a radio frequency (RF) link, but other such links have been proposedand implemented with varying degrees of success.

The coded signals received by receiver antenna coil 22 are provided tostimulator unit 20. The stimulator unit 20 is connected via a conductoror lead 24 to an intracochlea electrode array 26 mounted in the cochlea28 of the recipient. The received signals are therefore applied by theelectrode array 26 to the basilar membrane 30 of the recipient and nervecells within the cochlea 28 to effect stimulation of the auditory nerve32 to provide a hearing sensation for the recipient.

In the embodiments of cochlear implant system 10 of FIG. 1, externalspeech processor unit 12 is configured to be worn behind outer ear 34 ofthe recipient, and is referred to as a Behind-The-Ear (BTE) unit orsimply BTE. That is, speech processor unit 12 has sufficiently smalldimensions to be mounted behind outer ear 34. As shown, external speechprocessor unit 12 has therein or thereon microphone 36.

Embodiments of speech processor unit 12 are described below withreference to FIG. 2. As shown in FIG. 2, speech processor unit 12comprises a pre-amplifier and ADC module 40. Microphone 36 (FIG. 1)provides auditory inputs pre-amplifier and ADC module 40. Pre-amplifierand ADC module 40 may be implemented as a single module which maynormally draw power supplied by a bias circuit 42. The bias circuit mayhave a power down control operable under the control of the signalprocessor. Bias circuit 42 has a power-down control. When the power-downcontrol is activated, module 40 ceases operation. When the module 40ceases operation, it is put in a mode which draws only a relativelyminute amount of power.

The auditory inputs are pre-processed by pre-amplifier and ADC module40, and provided to a signal processor 38 which my comprise a digitalsignal processor. Data from signal processor 38 is fed to a dataencoder/formatter 48. The formatter 48 is used to send stimulationcommands and power across a transcutaneous link 50 tostimulator/receiver unit 21 of internal component 18 of cochlear implantsystem 10. Thus, the formatter may feed signals in the form ofstimulation commands, being coded sound signals, and power signals.Transcutaneous link 50 is made up of the transmitter antenna coil 16 ofthe external component 14 and the receiver antenna coil 22 of theimplant 18.

Transcutaneous link 50 may also be used to receive messages frominternal component which may be fed back via formatter 48 to signalprocessor 38. Specifically, signal processor 38 is configured tointerrogate internal component 18 and to receive messages back frominternal component 18 via formatter 48. When stimulation commands are tobe sent by signal processor 38 to internal component 18, the informationis encoded by the formatter 48 into a coded signal, being stimulationcommands representative of the sound signal received from the microphone36.

Signal processor 38 analyses received sound signals from the microphone36. The received sound signals are split up into frequency bands inaccordance with the tonotopic arrangement of the electrodes of electrodearray 26. Signal processor 38 analyses the amplitude of the signals ineach discrete frequency band in accordance with a specific soundprocessing strategy. For example, signal processor 38 can detect the “n”largest outputs for each filter channel, measure the amplitude of eachfilter channel and rank them accordingly.

Following frequency analysis and processing of the sound signals, signalprocessor 38 can access data allocating each frequency band to anelectrode pair of electrode array 26 from a memory 46. Memory 46 alsocontains psychophysical data, such as threshold and comfort levels ofthe recipient as mapped from each of the electrodes of the electrodearray 26. Using the above information, the sound signal is mapped to arecipient's electrode array 26 by selecting the electrodes assigned tothe particular frequency and choosing a level between comfort andthreshold to represent the loudness of that frequency component.

Also as shown, speech processor unit 12 includes a power source, shownby internal batteries 44, which provides power to the other componentsof speech processor unit 12. The power provided by batteries 44 is alsotranscutaneously transmitted to internal component 18. It is a desire ofthe industry to reduce power consumption of cochlear implant 10 so thatthe batteries 44 require replacement as infrequently as possible.

Speech processor unit 12 also includes an oscillator 52. Oscillator 52generates a master clock signal 78 used by all components of speechprocessor unit 12.

Speech processor unit 12 is, where applicable, made using CMOS circuitryfor all digital circuits. In particular, CMOS circuitry is used forsignal processor 38, formatter 48 and memory 46. In addition, oscillator52 is a CMOS design which draws approximately 100 μA or less.

In embodiments of the present invention, oscillator 52 provides itsoutput to a pause-and-gate circuit 54. Pause-and-gate circuit 54consists of a low-power counter that gates the clock from oscillator 52to signal processor 38. In a normal operating mode, circuit 54 passesclock signal 78 from oscillator 52 to signal processor 38 and, fromthere, to the rest of speech processor unit 12. In a pause mode, circuit54 interrupts clock signal 78 to signal processor 38 and waits for adelay signal from signal processor 38. Signal processor 38 controls whenpause-and-gate circuit 54 enters its pause mode.

As noted above, embodiments of the present invention are generallydirected to reducing the power consumption of a cochlear implant uponthe detection of one or more parameters. In one embodiment of theinvention, the parameter monitored by the speech processor unit may bethe proximity of the external component to the internal component. Inthese embodiments, the speech processor unit is configured tocontinually or periodically determine of the external component is inproximity to the internal component by sending an interrogation signalto determine if the internal component is present. It will beappreciated that, should the external unit have been removed from therecipient's body, normally behind the recipient's ear, the internalcomponent will not be detected by the digital signal processor, and thusthe external component is not in proximity to the internal component.This may be taken as an indication that the external component is notbeing used, for example, due to the recipient being asleep or in asituation where the cochlear implant is not being used, for example,while bathing, etc. As described in greater detail below, if theexternal component is not in proximity to the internal component, thepower consumption of the cochlear implant system may reduced.

In another embodiment of the invention, the parameter monitored by theunit may be motion of the recipient. Thus, the unit may include amotion-detecting means. The motion-detecting means may be in the form ofa mercury switch. In the absence of motion, the switch may cause thespeech processor unit to reduce the power consumption of the cochlearimplant.

In yet a further embodiment of the invention, the parameter beingmonitored may be a value of reflected impedance as “seen” by the speechprocessor unit. When the receiver antenna coil has been removed, thereflected impedance as detected by the signal processor may be muchhigher than when the receiver antenna coil is present. Thus, byappropriate calculation to take into account current drawn duringstimulation and the current drawn by the components of the unit itself,the signal processor can determine whether or not the implantedcomponent is present. If not, the signal processor may followsubstantially the same procedure as described above with reference tothe first embodiment.

In certain embodiments of the present invention, external speechprocessor unit 12 operates as follows to reduce the power consumption ofcochlear implant system 10. The operation is described with reference toFIG. 5 and 6. The following discussion assumes that cochlear implantsystem 10 is operating under normal conditions and is processing sound.All circuits of external speech processor unit 12 are active.Periodically, for example, once every 10 seconds, signal processor 38polls internal component 18 with a message that includes a telemetrycommand at step 100 in FIG. 5 and awaits a reply 102. If signalprocessor 38 receives a response from the internal component 18, it“knows” that the internal component is present and in proximity toexternal component 14. As such, signal processor 38 continues processingsound 104. If, however, signal processor 38 does not receive a telemetryresponse, it can send one or more telemetry commands to internalcomponent 18 to detect if its receiving antenna coil 22 is present.After confirming that the receiving antenna coil 22 is not present,speech processor unit 12 assumes that this is because the receivingantenna coil 22 is not in communication with transmitting antenna coil16 of external component 14. This is taken as a message to “switch off”,i.e. to enter an idle state or shutdown mode as shown at step 106 (FIGS.5 and 6).

Signal processor 38 (or “DSP”) then starts its shut-down routine asdescribed with reference to FIG. 6 of the drawings. This routineinvolves one or steps including, disabling bias circuit 42 at step 108.Disabling the bias circuit 42 causes pre-amplifier and ADC module 40 toenter a low-power state as shown 110. The shutdown routine may alsoinclude signal processor 38 disabling or stopping the sending ofcommands, encoded signals or power to internal component 18, and/ordisabling or stopping the accessing of memory 46 by signal processor 38at step 112. When signal processor 38 stops accessing memory 46, thiscauses memory 46 to stop drawing power from batteries 44 as shown at114.

Finally, the shut-down routine may include signal processor 38 sending a“pause” signal, via a pause input 64 (FIGS. 2 and 4) to pause-and-gatecircuit 54 at step 116. This causes circuit 54 to enter its pause modewhereby clock signal 78 from oscillator 52 to signal processor 38 isinterrupted as shown at 118.

Following the implementation of all of the above steps, all CMOScircuits are in an idle state 120. Oscillator 52 and pause-and-gatecircuit 54 continue to draw power from the batteries 44 but no othercomponents do or, more accurately, the power drawn is so small as to berelatively negligible. In this state, the power drawn by speechprocessor unit 12 is that drawn by oscillator 52 and is typically lessthan 100 μA.

Speech processor unit 12 remains in the idle state for the delaygenerated by pause-and-gate circuit 54. A typical value for this delayis of the order of about 1 second. When this delay is completed, clocksignal 78 from oscillator 52 to signal processor 38 is re-applied bypause-and-gate circuit 54 to signal processor 38. Signal processor 38then sends a telemetry command to the internal component 18 as shown at122 in FIG. 5 of the drawings. Assuming the internal component 18 isstill not present (in proximity to external component), signal processor38 will receive no response. This causes signal processor 38 to instructpause-and-gate circuit 54 to enter its pause mode once again.

The unit 12 can remain in this mode for any time period ranging fromminutes to many hours as long as the transmitter antenna coil 16 is notplaced on the recipient's head which would re-establish thetranscutaneous link 50 to the implant 18. Thus, if the recipient hasplaced the transmitter antenna coil 16 in register with the receiverantenna coil 22, the link 50 is re-established. Thus when the signalprocessor 38 again sends a detection command to internal component 18,it will receive a response. It then knows that it has to startprocessing sound again. In this configuration, signal processor 38re-enables pre-amplifier and ADC module 40, waits a short time for anyanalogue circuitry to stabilise and recommences sound processing.

A typical speech processor unit 12 draws between 2-25 mA when operating.For the sake of the example, it is assumed that the current drawn is 15mA on average. It is also assumed that it takes 1 ms for the speechprocessor to re-activate, send a telemetry command, receive a reply andshut down again. Thus, with a signal processor 38 having a 10 MHz clock,this allows 1000 instructions for operation which is well within thecapabilities of a standard signal processor 38. In its idle state, unit12 draws approximately 100 μA. Thus, the average current drawn by speechprocessor unit 12 is approximately 105 μA. This is sufficiently low thata battery could provide this power for a long period of time. A typicalbattery has a capacity of 300 mAH. Thus, the processor unit 12 canoperate for nearly 3000 hours in this mode.

An implementation of the pause-and-gate circuit 54 is shown in FIG. 4 ofthe drawings. Circuit 54 has a pause input 64 that, as described above,is asserted by signal processor 38 when it has failed to detect internalcomponent 18 and so initiates the low-power routine. A delay module 66allows the DSP clock signal 78 to continue while signal processor 38clears pause input 64 to prevent unit 12 from locking up.

Further, as indicated above, oscillator 52 provides clock signal 78 forthe signal processor 38 and a clock signal 80 for a counter 68 of thepause-and-gate circuit 54.

Counter 68 sets the time for the “idle” state for unit 12. Counter 68has two outputs, an “Overflow” output 70 and an “Overflow*” output 72.The “Overflow” output 70 is asserted when the count has reached itsmaximum value. The “Overflow*” output 72 is the logical inverse of“Overflow” output 70. An AND gate 74 gates the “Overflow*” output 72 andthe oscillator 52 to provide the clock signal 80 for the counter 68. Asecond AND gate 76 gates the “Overflow” output 70 and the oscillator 52to provide the clock signal 78 for the signal processor 38.

Circuit 54 operates in the following manner. Under normal operatingconditions, when internal component 18 is detected, oscillator 52 isrunning and the Overflow output 70 is high. This allows clock signal 78to toggle and drive signal processor 38. The “Overflow*” output 72 islow so the AND gate 74 prevents oscillator 52 clocking counter 68.

To enter the low-power state, signal processor 38 sets the pause signal64. This initiates a pulse in the delay module 66. Signal processor 38then resets the pause signal 64. The delay module 66 has as many stagesas the number of clock cycles required by signal processor 38 to clearthe pause signal 64 to allow the pause signal 64 to be reset.

A pulse from the delay module 66 resets counter 68. Resetting of counter68 causes the “Overflow” output 70 going low which, in turn, results inclock signal 78 to the signal processor 38 being inhibited by AND gate76. The “Overflow*” output 72 goes high so oscillator 52 clocks counter68 via the AND gate 74. Counter 68 has sufficient stages that it cancount for the time for which unit 12 must be in its low-power state. Atthe end of this time, when counter 68 has reached its maximum countvalue, the “Overflow” output 70 goes high, allowing clock signal 78 tosignal processor 38 to resume. The “Overflow*” output 72 goes lowblocking the clock signal 80 to the counter 68. Clock signal 78 is thenavailable to signal processor 38, allowing it to check for the presenceof the implant 18.

In a variation of the invention, pause-and-gate circuit 54 can beimplemented as software in signal processor 38 if signal processor 38 isconfigured to run a software timer at sufficiently low power.

Further, if signal processor 38 has a set of event counters for timingreal-time events, these might be suitable for implementing thepause-and-gate function. These counters generate an interrupt when theyhave run for the pre-allocated time. The interrupt starts the signalprocessor 38 running again.

As noted above, the above described embodiments of the present inventionillustrate implementations in which cochlear implant system 10 enters areduced power state when the external component is not in proximity tothe internal component. In another embodiment of the invention,illustrated in FIG. 3 of the drawings, speech processor unit 12 includesa motion detecting mechanism in the form of a motion detecting switch56. The motion detecting switch 56 is connected to the pause-and-gatecircuit 54. In the absence of motion for a predetermined period of time,switch 56 causes the pause-and-gate circuit 54 to enter its pause modeinterrupting clock signal 78 from the oscillator 52 to the signalprocessor 38. This causes unit 12 to enter its idle state, as describedabove. It would be appreciated that any of the above described methodsfor reducing power may be used together or individually to reduce thepower consumption of the cochlear implant system 10 in the absence ofmotion or when the external component is not in proximity to theinternal component.

Conveniently motion switch 56 is a mercury switch having a pair ofcontacts 58 which, when switch 56 is closed, is bridged by a blob ofmercury 60. Contacts 58 and mercury 60 are housed in an envelope 62 of anon-conductive material, such as glass. The switch 56 is arranged sothat, in the absence of motion, mercury 60 does not bridge contacts 58,thereby disabling switch 56. Movement of the recipient is required tomove mercury 60 so that it bridges contacts 58. When this occurs,pause-and-gate circuit 54 enters it normal mode.

Thus, as long as the external component 14 of the implant 12 is leftidle, for example, on a bedside table during the night while therecipient is a sleep, speech processor unit 12 will remain in its idlemode. If the unit 12 is, for example, bumped then the signal processor38 will be activated, but may further detect that internal component 18is absent and the unit 12 will again be placed in its idle state.

Yet a further embodiment of the invention relies on reflected impedance.In this embodiment of the invention, the reflected impedance of implantreceiver antenna coil 22 affects the input impedance of transmitterantenna coil 16 as detected by signal processor 38. This embodimentoperates in a similar manner to the implementation described above withreference to FIG. 2 of the drawings except that signal processor 38measures current used to drive the implant 18.

For this embodiment of the invention, battery 44 has a small resistor inseries forming an ammeter so that signal processor 38 can measure thesupply current.

Since the supply current of the speech processor unit 12 varies with thestimulation rate, signal processor 38 must compensate for the rate atwhich it is sending radio frequency (RF) signals across the link 50 theimplant 18. For this purpose the signal processor performs the followingsteps:

-   -   records the rate at which it sends RF frames to the implant 18;    -   measures the current drawn from the battery 44 using the        ammeter;    -   subtracts from the values measured, the current drawn by the        signal processor 38 itself, the analogue circuitry etc.;    -   from the previous step, calculates the power drawn from the        battery 44 for each stimulation;    -   from the calculation in the preceding step, determines whether        or not the implant 18 is present.

Typically, when signal processor 38 is driving internal component 18 itdraws a current of about 12 mA maximum. When receiver coil 22 is absent,the drawn current can reach levels of up to 80 mA. As a result, thislarge difference in values means that errors from the ammeter or fromthe calculation are not critical.

Accordingly, it is an advantage of the invention that a cochlear implantsystem 10 is provided which omits a mechanical on/off switch in theexternal processor. Such a mechanical switch is prone to failure as itis used many times by the recipient. In addition, because of the smallsize of behind the ear external speech processor units 12, the switchitself is also of small dimensions. This makes it difficult for olderpeople or less dexterous people to manipulate such switches. Because theinvention obviates the need for a switch, this problem is also overcome.

In addition, one of the causes of failures of external speech processorunits 12 is the ingress of moisture. Often the ingress of moisture isthrough the aperture in a casing of the external speech processor unitfor a lever of an on/off switch. Once again, because the on/off switchis able to be eliminated in the present invention, this problem is also,to at least a large extent, overcome. Thus, this renders the system 10more versatile as it is now possible for recipients to use the system 10even in wet environments such as when showering or out in the open andbeing caught in the rain.

It will be appreciated by persons skilled in the art that numerousvariations and/or modifications may be made to the invention as shown inthe specific embodiments without departing from the spirit or scope ofthe invention as broadly described. The present embodiments are,therefore, to be considered in all respects as illustrative and notrestrictive.

All documents, patents, journal articles and other materials cited inthe present application are hereby incorporated by reference.

The invention described and claimed herein is not to be limited in scopeby the specific preferred embodiments herein disclosed, since theseembodiments are intended as illustrations, and not limitations, ofseveral aspects of the invention. Any equivalent embodiments areintended to be within the scope of this invention. Indeed, variousmodifications of the invention in addition to those shown and describedherein will become apparent to those skilled in the art from theforegoing description. Such modifications are also intended to fallwithin the scope of the appended claims.

1. A method of reducing the power consumption of a cochlear implantcomprising an external component including a speech processor unitconfigured to be worn by a recipient, and an internal component, themethod comprising: monitoring by the speech processor unit the proximityof the external component unit to the internal component; determining bythe speech processor unit that the external component is not inproximity to the internal component; and causing the external componentto enter an idle state of reduced power consumption when the speechprocessor unit determines that the external component is not inproximity to the internal component.
 2. The method of claim 1, whereinthe speech processor unit comprises a pre-amplifier and ADC module thatreceives auditory inputs from a microphone, and wherein causing theexternal component to enter an idle state of reduced power consumptioncomprises: causing the preamplifier and ADC module to enter a low powerstate.
 3. The method of claim 2, wherein the speech processor unitfurther comprises a bias circuit to control the operation of thepre-amplifier and ADC module, and wherein causing the preamplifier andADC module to enter a low power state comprises: disabling the biascircuit.
 4. The method of claim 1, wherein the external componenttransmits signals to the internal component, and wherein causing theexternal component to enter an idle state of reduced power consumptioncomprises: disabling the transmission of signals from the externalcomponent to the internal component.
 5. The method of claim 1, whereinthe speech processor unit comprises a memory, and wherein causing theexternal component to enter an idle state of reduced power consumptioncomprises: disabling the draw of power by the memory.
 6. The method ofclaim 5, wherein the speech processor unit comprises a signal processorthat accesses the memory, and wherein disabling the draw of power by thememory comprises: disabling the access of memory by the signalprocessor.
 7. The method of claim 1, wherein the speech processor unitfurther comprises a signal processor and an oscillator providing a clocksignal to the elements of the speech processor unit, and wherein causingthe external component to enter an idle state of reduced powerconsumption comprises: interrupting the clock signal from the oscillatorto the signal processor causing clock dependent elements to enter anon-power consuming idle state for a period of time
 8. The method ofclaim 7, wherein the speech processor unit further comprises apause-and-gate circuit, and wherein interrupting the clock signal fromthe oscillator to the signal processor comprises: sending a pause signalfrom the signal processor to the pause-and-gate circuit.
 9. A method ofreducing the power consumption of a cochlear implant comprising anexternal component including a speech processor unit configured to beworn by a recipient, and an internal component, the method comprising:monitoring by the speech processor unit motion of the speech processorunit; determining that the speech processor unit is not motion; andcausing the external component to enter an idle state of reduced powerconsumption when the speech processor unit determines that the speechprocessor unit has ceased movement.
 10. The method of claim 9, whereinthe speech processor unit comprises a pre-amplifier and ADC module thatreceives auditory inputs from a microphone, and wherein causing theexternal component to enter an idle state of reduced power consumptioncomprises: causing the preamplifier and ADC module to enter a low powerstate.
 11. The method of claim 10, wherein the speech processor unitfurther comprises a bias circuit to control the operation of thepre-amplifier and ADC module, and wherein causing the preamplifier andADC module to enter a low power state comprises: disabling the biascircuit.
 12. The method of claim 9, wherein the external componenttransmits signals to the internal component, and wherein causing theexternal component to enter an idle state of reduced power consumptioncomprises: disabling the transmission of signals from the externalcomponent to the internal component.
 13. The method of claim 9, whereinthe speech processor unit comprises a memory, and wherein causing theexternal component to enter an idle state of reduced power consumptioncomprises: disabling the draw of power by the memory.
 14. The method ofclaim 13, wherein the speech processor unit comprises a signal processorthat accesses the memory, and wherein disabling the draw of power by thememory comprises: disabling the access of memory by the signalprocessor.
 15. The method of claim 9, wherein the speech processor unitfurther comprises a signal processor and an oscillator providing a clocksignal to the elements of the speech processor unit, and wherein causingthe external component to enter an idle state of reduced powerconsumption comprises: interrupting the clock signal from the oscillatorto the signal processor causing clock dependent elements to enter anon-power consuming idle state for a period of time
 16. The method ofclaim 15, wherein the speech processor unit further comprises apause-and-gate circuit, and wherein interrupting the clock signal fromthe oscillator to the signal processor comprises: sending a pause signalfrom the signal processor to the pause-and-gate circuit.
 17. A cochlearimplant comprising: an internal component configured to be implanted ina recipient of the cochlear implant; and an external component includinga speech processor unit configured to be worn by the recipient, thespeech processor unit comprising: a signal processor configured todetermine if the external component is in proximity to the internalcomponent, and to place the external component in an idle state ofreduced power consumption when the external component is not inproximity to the internal component.
 18. The cochlear implant of claim17, wherein the external component further comprises a transmitterconfigured to transmit a telemetry command to the internal component,and wherein the signal processor is configured to determine if theexternal component is in proximity to the internal component based onthe response by the internal component to the telemetry command.
 19. Thecochlear implant of claim 18, wherein in the absence of a response bythe internal component to the telemetry command the signal processor isconfigured to determine that the external component is not in proximityto the internal component.
 20. The cochlear implant of claim 17, whereinthe signal processor is configured to determine if the externalcomponent is in proximity to the internal component by measuring theimpedance between the signal processor and the internal component. 21.The cochlear implant of claim 17, wherein the external component furthercomprises: a pre-amplifier and an analog-to-digital converter (ADC)module configured pre-process auditory inputs from a microphone; and abias circuit configured to control the supply of power to thepre-amplifier and ADC module, wherein the signal processor is configuredto place the external component into the idle state by disabling thesupply of power from the bias circuit to the module.
 22. The cochlearimplant of claim 17, wherein the external component is configured totransmit signals to the internal component, and wherein the signalprocessor is configured to place the external component into the idlestate by disabling the transmission of the signals from the externalcomponent to the internal component.
 23. The cochlear implant of claim17, wherein the external component further comprises: a battery supplyfor supplying power to one or more components of the external component,and wherein the signal processor is configured to place the externalcomponent into the idle state by disabling the supply of power from thebattery supply to the one or more components.
 24. The cochlear implantof claim 17, wherein the external component further comprises: a memoryconfigured to store psychophysical data of a recipient of the cochlearimplant, and wherein the signal processor is configured to place theexternal component into the idle state by disabling access to thememory.
 25. The cochlear implant of claim 17, wherein the externalcomponent further comprises: a controller operable under the control ofthe signal processor; and an oscillator configured to deliver a clocksignal to the signal processor, wherein the signal processor isconfigured to send a pause signal to the controller so as to interruptthe clock signal from the oscillator to the signal processor when thesignal processor determines that the external component is not inproximity to the internal component.
 26. A cochlear implant comprising:an internal component configured to be implanted in a recipient of thecochlear implant; and an external component including a speech processorunit configured to be worn by the recipient, the speech processor unitcomprising: a monitor configured to detect motion of the speechprocessor unit; and a signal processor configured to place the externalcomponent in an idle state of reduced power consumption when the monitordetermines that the external component has ceased movement.
 27. Thecochlear implant of claim 26, wherein the monitor comprises a mercuryswitch.
 28. The cochlear implant of claim 26, wherein the signalprocessor is configured to place the external component in an idle stateof reduced power consumption after the speech processor has ceasedmovement for a period of time.
 29. The cochlear implant of claim 26,wherein the external component further comprises: a pre-amplifier and ananalog-to-digital converter (ADC) module configured pre-process auditoryinputs from a microphone; and a bias circuit configured to control thesupply of power to the pre-amplifier and ADC module, wherein the signalprocessor is configured to place the external component into the idlestate by disabling the supply of power from the bias circuit to themodule.
 30. The cochlear implant of claim 26, wherein the externalcomponent is configured to transmit signals to the internal component,and wherein the signal processor is configured to place the externalcomponent into the idle state by disabling the transmission of thesignals from the external component to the internal component.
 31. Thecochlear implant of claim 26, wherein the external component furthercomprises: a battery supply for supplying power to one or morecomponents of the external component, and wherein the signal processoris configured to place the external component into the idle state bydisabling the supply of power from the battery supply to the one or morecomponents.
 32. The cochlear implant of claim 26, wherein the externalcomponent further comprises: a memory configured to store psychophysicaldata of a recipient of the cochlear implant, and wherein the signalprocessor is configured to place the external component into the idlestate by disabling access to the memory.
 33. The cochlear implant ofclaim 26, wherein the external component further comprises: a controlleroperable under the control of the signal processor; and an oscillatorconfigured to deliver a clock signal to the signal processor, whereinthe signal processor is configured to send a pause signal to thecontroller so as to interrupt the clock signal from the oscillator tothe signal processor when the monitor determines that the externalcomponent has ceased movement.